This invention relates to car signaling systems, and more particularly to a signaling system of the kind above described in which means are provided for detecting accurately the interval between successive cars.
In traffic facilities such as railways in which trains run along trackage, each train is required to run at an allowable speed determined by the conditions of rails while maintaining a safe interval between it and the preceding train. This interval is desirably as small as possible so that more trains can run along the same track. It is therefore necessary for each train to detect the distance between it and the preceding train, and if possible, those factors such as the speed and deceleration of the preceding train, and to control the running speed thereof depending on the running condition of the preceding train, so that it can run while maintaining an allowable minimum interval between it and the preceding train.
A car signaling system has been commonly employed to meet the above requirement, in which the track is divided into a plurality of block sections, and a suitable detecting device is provided in each of these block sections for detecting the presence or absence of a car in the specific block section. In the known car signaling system, the detecting device in each block section detects the presence of a car in the block section when the two rails in the block section are short-circuited by the rail-engaging wheels of the car, and the result of detection is transmitted to means provided for detecting the interval between this car and the preceding car running along the same track.
However, this known car signaling system is solely applicable to the case in which both the rails and the rail-engaging wheels of cars are of electrically conductive material. Thus, this known car signaling system is defective in that it is not applicable to cars adapted for running with rail-engaging wheels of, for example, rubber. Further, in order to detect the interval between the cars with high precision, the track must be divided into many block sections of considerably short length resulting in the increase in the number of block sections. Thus, the known car signaling system is defective in that the number of detecting means for detecting the presence of the cars in the block sections is increased resulting in high equipment costs.